Mercury vapor lamp



Sept. 6, 1938. J. w. MARDEN ET AL MERCURY VAPOR LAMP Filed Oct. 8, 1936 INVENTOR JIM/7459f ATTORNEY Patented Sept. 6, 1938 UNITED STATES PATENT OFFICE MERCURY VAPOR LAMP Application October 8, 1936, Serial N0. 104,596

12 Claims. (Cl. 116-122) This invention relates to a discharge lamp and more particularly to a high intensity lamp employlng mercury or other metallic vapor.

In our copending application Serial No. 49,448, flied November 13, 1935, a lamp is shown and described in which the importance of the relation between the bulb length. bulb diameter, pressure, and other factors are pointed out. In lamps made in accordance with the teachings oi the above mentioned copending application, although satisfactory and of importance in the lamp art, certain manufacturing problems arise particularly in controlling the quantity of mercury which, in such lamps, must be so limited in amount that during the operation of thelamp the entire deposit of mercury is vaporized.

In accordance with the present invention a lamp is produced in which an excess amount of mercury is employed; that is, the amount of liquid mercury introduced into the bulb is greater than is necessary to support the desired arc discharge. A supply source of mercury is provided and after a suflicient amount of mercury from the/source is vaporized to produce the discharge, it passes to cooler portions of the bulb and condenses to liquid form. The bulb and its operating elements arev so constructed and arranged that the condensed or liquid mercury flows back to the supply source. Thus a continuous replenishment of the source is effected. resulting in a continuous operation of the lamp in 8. current of mercury vapor.

It is an object of the present invention to pro vide a mercury vapor lamp of simple construction and efficient operation.

Another object of the invention is to provide a high intensity mercury vapor lamp in which a continuous supply of vaporized mercury is produced.

A further object of the invention is to provide a mercury vapor lamp containing an amount of provision of anarc lamp containing mercury, in

excess ofthat needed to maintain the discharge, and having a chamber or portion projecting above the are for condensing mercury, when its vapor pressure exceeds that desired, and allowing it to return by gravity for redistillation, so that the arc operates in a stream mercury vapor.

Other objects and advantages of the invention will bemore clearly understood by reference to the following description together with the accompanying drawing in which:

Fig. .1 is a longitudinalsectional view, with parts in elevation, of one form of lamp constructed in accordance with the present invention, and having a partition at one end of theof upwardly ascending bulb to provide a condensation chamber;

- the lines of that shown in Fig. 1, but in which a compartment is provided at each end of the bulb, a wiring diagram, disclosing one way of using the lamp, being illustrated;

Fig. 4 is a transverse sectional view on the line IV-IV of Fig. 3, looking in the direction of the arrows; and

Fig. '5 is a fragmentary view, corresponding to Figs. 1 and 3, but showing a partition in diagonal relation to the "bulb wall.

Although the present invention may be employed in connection with various types of discharge lamps, a preferred embodiment, illustrated in Figs. 1 and 2, is a lamp with a 'bulb ill of hard glass, quartz, pyrex, or the like, having a reentrant tube H terminating in a press l2 through which lead wires or conductors i3 and It are sealed. Lead wire it connects with a conductive support IE to which is connected one end of a rigid conductive support rod It. This rod is encased in a sleeve ii of glass, or other suitable insulating material, and its other end is secured to an extension -member iii. The conducting member i8 extends transversely of the bulb and carries an electrode l3, desirably located on the longitudinal axis of said bulb. The lead wire it is connected to a rigid support member 2| which also extends transversely of the bulb and carries an electrode 22, desirably alinedwith the elecof nickel wire mesh, the interstices of which are v filled or impregnated with electron emission material such as barium oxide, strontium oxide, another alkali earth, or mixtures thereof. When preferably of simi- I the supporting body or mesh has been suitably impregnated or filled with the electron emission material, outer portions of the latter are desirably removed so that the outer face of the mesh or enclosing material is exposed.

Each disk 23 is desirably carried by the corresponding conductor extending from the members ill or 2! and associated therewith is the bridge piece 2, preferably formed of refractory metal such as tungsten, which becomes effectively electron emissive at high temperatures, desirably having its ends welded to the corresponding conductor and extending across the inner or opposite surface of the disk 23, with its intermediate portion 25 bent toward the other electrode so as to be spaced from the surface of the associated disk 23. In this way electrodes are provided which have activated portions adapted to emit electrons at relatively low temperatures, and other portions which become electron emitting at higher temperatures and carry the main portion of the are or discharge when the lamp is in operation, thereby protecting the electron .emitting disks from deterioration, all as more fully described and claimed in our copending application Serial No. 733,168, filed June 30, 1934.

Within the bulb is a quantity of mercury 26. A small quantity of arare gas, such as neon, may be introduced into the bulb to produce an initial discharge which heats the body of mercury, producing vapor which supports a relatively heavy flow of current between the electrodes. As the temperature of the device rises, more mercury is vaporized and, by reason of the voltage between the electrodes, an intensive glow occurs in the form of an ionized column of mercury.

During operation, the mercury is vaporized and travels upward to all parts of the bulb. In accordance with the present invention, a condensatlon chamber is provided at 21 so that any mercury vapor reaching it is condensed and flows back to the initial supply. The chamber 2'! of the present embodiment includes the wall of the bulb and the wall of the partition 28, desirably formed of mica or the like, and surrounds the reentrant tube H which serves as a heat absorbing element.

One or more apertures or notches 29, provided in the partition 28, afiord communication between the cooling chamber 21 and the discharge chamber of the lamp, which latter chamber is designated by the reference numeral 30. The discharge between the electrodes l9 and 22 takes the form of an arc stream of high intensity extending in a substantially straight line between replenished as the lamp operates, making it posconductor or extension centering the lower electrode I 9*. In order to accomplish this purpose, a second partition 3|, similar to the partition 28"- in the upper part of the bulb I is provided, saidsecond partition, however, being apertured to not only receive and center the free end of the conductor 32 from the electrode i9, but also apertured, as indicated at 33, to allow free transmission of heat tothe mercury 26- therebeneath. I

In order to position the partition as close as possible to the end of the bulb and mercury contained therein, the connection between the support rod "5 and the conductor 32 is made by a member I8 disposed above rather than below said partition. In this way, the lower electrode [9 is positively centered in the bulb i0 independent of the rigidity of the support red It.

It is, of course, desired to use a lamp such as described in the present application either with a ballast impedance, such as indicated at 34 in Fig. 3, or with a transformer which will automatically limit the current to a certain figure. If the pressure available is not more than 200 volts, as say between 100 and 200, it is desirable to use a starting tip, as designated by the reference character 35 in Fig. 3, disposed adjacent the electrode 22 and connected to the lead to the other electrode through a high resistance 36, as by means. of a lead-in wire 31.

In the embodiment of Figs. 3 and 4, the electrode 22 is connected through two leading-in conductors and N terminating in rigid support members M and 2l although the con-- struction is merely alternative as providing a slightly more rigid structure and adapting the tube for a customary four-prong base.

Referring now to the embodiment of our invention illustrated in Fig. 5, a construction is disclosed which may be identical with either that of Fig, 1, or that of Fig. 3, except that the partition 28 adjacent the press is inclined with respect to the longitudinal axis of the bulb to more readily drain oif the condensed mercury.

'A lamp constructed in accordance with the "present invention may include a bulb of five and a quarter inches in length and one and a quarter inches in diameter. One to two cubic centimeters'of mercury is desirably employed in each bulb. The device, with argon filling at a pressure of from 10 to 20 millimeters, may .be operated at sixty volts alternating current to produce an arc stream of high intensity.

A lamp with the dimensions above enumerated may be operated at 200 watts. Some device is employed, such as a suitable transformer or choke coil, to cause the potential drop in the lamp when operating under normal conditions, to be 60 volts with acurrent of 3.3 amperes. In other words, for example, on 220 volts an iron core impedance should be employed of a size suiiicient to limit the current delivered so that the lamp gets 200 watts duringv operation. Larger and smaller lamps can be made in proportion as desired.

Although preferredembodiments of our invention have been illustrated, it will be understood that modifications may be made within the spirit the electrode adjacent thereto and the other extending to said other electrode, a pool of mercury in said bulb heated by the'discharge-irom said electrodes, to provide vapor. for supporting said discharge, and a chamber around said press and above said discharge to condense surplus vapor and return it to said pool.

2. A metallic vapor discharge device comprising a tubular bulb, electrodes in said bulb, a source of metallic vapor supply in said bulb to provide a conductive vapor to produce an arc discharge be- .tween said electrodes, a mere partition separating one end portion of said bulb from the remainder to provide a cooling chamber to receive and condense metallic vapor formed in said bulb in excess of that required for said arc discharge, said partition having an aperture for the flow of said condensed vapor back to the source of supply.

3. A mercury discharge device comprising a tubular bulb, electrodes in said bulb, a source of supply for mercury, vapor in said bulb to provide means to conduct an arc discharge between said electrodes, a cooling chamber defined by a mere partition separating one end portion 01' said bulb from the remainder to receive and condense mercury vapor formed in said bulb in excess of that required for said are discharge, and means for returning said condensed mercury to said source of supply. Q

4. A mercury vapor discharge device comprising a bulb, electrodes disposed one adjacent each end of said bulb, a pool of mercury in said bulb heated by the discharge from said electrodes to provide vapor for supporting said discharge, and a mere partition disposed above said discharge to divide of! a portion of the bulb to provide a cooling chamber for the condensation of surplus vapor.

5. A mercury vapor discharge device comprising a bulb, electrodes disposed one adjacent each end of said bulb, each electrode comprising a portion adapted to emit electrons at low temperature and another portion extending across the inner surface thereof and with an intermediate portion bent away so as to be spaced toward the other electrode for taking the main discharge when the device is in operation and protecting the electron emitting material,-a pool oi mercury in said bulb heated by the discharge from said electrodes to provide vapor for supporting said discharge, and a chamber above said discharge to condense surplus vapor and return it to said pool. 6. A metallic vapor discharge device comprising a tubular bulb having a press, leading-in conductors extending through said press, electrodes disposed one adjacent each end of saidbulb, one of said leading-in conductors being connected to the electrode adjacent thereto and the other traversing substantially the length of the bulb and connected to the other electrode, an insulating sleeve protectingthe tube-traversing conductor between said electrodes, a pool of mercury in said bulb heated by the discharge from said electrodes, and

a partition intersected byiboth conductors and serving to divide the portion adjacent said press during the operation or the device. a

'7. A metallic vapor discharge device comprising a tubular bulb having a press, leading-in conductors extending through said press, electrodes 3 ersing substantially the length of thebulb and connected to the other electrode, an insulating tition disposed adjacent the other end of saidbulb for centering the adjacent electrode.

8. A metallic vapor discharge device comprising a tubular bulb having a press, leading-in conductors extending through said press, electrodes disposed one adjacent each end of said bulb, one of said leading-in conductors being connected to the electrode adjacent thereto and the other traversing substantially the length of the bulb and connected to the other electrode, an insulating sleeve protecting the tube-traversing conductor betweensaid electrodes, a pool of mercury in said bulb heated by the discharge from said electrodes, and a partition intersected by both conductors and serving to divide the portion adjacent said press from the remainder of said bulb to providea cooling chamber for condensing surplus mercury vapor and returning it to said pool of mercury during the operation of the device, said partition being tilted with respect to the bulb axis to more readily drain mercury therefrom.

- 9. A vapor discharge device comprising an envelope, electrodes disposed therein, one adjacent each end of said envelope, each electrode comprising a portion activated to emit electrons at low temperatures and another portion extending across the inner surface thereof and with an intermediate portion bent away so as to be spaced toward the other electrode for taking the main discharge and protecting the activated material,

adjacent thereto and the other traversing substantialiy the entire length of the envelope and connected to the othere1ectrode,-insulating means protecting the envelope-traversing. conductor between said electrodes, mercury in said envelope heated by the discharge from said electrodes, a partition intersected by both conductors and serving to divide the portion adjacent one electrode from the remainder of the envelope, to provide a cooling chambertor condensing surplus mercury vapor, and another partition disposed adjacent the other electrode for centering the same.

11. A vapor discharge device comprising an envelope, leading-in conductors, electrodes disposed one adjacent each end of said envelope, one of said leading-in conductors being connected to the electrode adjacent thereto and the other trav-1 ersing substantially the length of the envelope and connected to the other electrode, insulating means protecting the envelope-traversing conductor between said electrodes, liquid mercury in said envelope heated bythe discharge between said electrodes, and a partition intersected by said conductors and serving to divide a portion adjacent enough of said envelope to connect with said other electrode, insulating means protecting said last mentioned conductor between said electrodes, a quantity of mercury in said envelope heated by the discharge in said device, and a portion of said envelope forming a cooling chamber around said press for condensing surplus mercury vapor during operation.

JOHN W. MARDEN. GEORGE MEISTER. 

